CN116096767A

CN116096767A - Method for forming graft layer, method for producing composite, and treatment liquid for forming graft layer

Info

Publication number: CN116096767A
Application number: CN202180054327.5A
Authority: CN
Inventors: 山根史帆里; 野口礼; 京本政之
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2020-09-10
Filing date: 2021-09-06
Publication date: 2023-05-09
Also published as: AU2021340988A1; WO2022054743A1; EP4212560A4; AU2021340988B2; JPWO2022054743A1; EP4212560A1; US20240010807A1

Abstract

A method for forming a graft layer having a graft chain equivalent to a conventional one or a longer one and/or having a graft layer equivalent to a conventional one or a thicker one is provided. The method for forming a graft layer according to one embodiment of the present invention comprises the steps of: a contact step of contacting a substrate containing a polymer A with a treatment liquid containing a compound B and a polymer C in a solvent D; in the contacting step, the polymer a constituting at least a part of the surface of the substrate is graft polymerized with the compound B.

Description

Method for forming graft layer, method for producing composite, and treatment liquid for forming graft layer

Technical Field

The present invention relates to a method for forming a graft layer, a method for producing a composite, and a treatment liquid for forming a graft layer.

Background

There is known a technique of forming a polymer film by graft polymerizing a compound on the surface of a substrate. In addition, a method of forming a polymer film using an aqueous treatment solution containing a water-soluble inorganic salt is known.

Disclosure of Invention

The method for forming a graft layer according to one embodiment of the present invention includes a contact step of contacting a substrate containing a polymer A with a treatment liquid containing a compound B and a polymer C in a solvent D. The contacting step includes a polymerization step of graft polymerizing the compound B to the polymer a constituting at least a part of the surface of the substrate.

In addition, the treatment liquid according to one embodiment of the present invention is a treatment liquid for forming a graft layer in which the compound B is graft polymerized on at least a part of the surface of a substrate containing the polymer a, wherein the compound B and the polymer C are contained in the solvent D.

Drawings

Fig. 1 is a schematic diagram illustrating the effect of the excluded volumes.

Fig. 2 is a schematic diagram illustrating the gel effect.

Fig. 3 is a schematic view of an artificial femoral joint 1 according to an embodiment of the present invention.

FIG. 4 is a schematic view of an acetabular cup according to an embodiment of the invention.

Fig. 5 is a graph showing the relationship between the concentration of 2-methacryloyloxyethyl phosphorylcholine in the treatment solutions of example 1 and comparative example 1 and the static contact angle of water.

FIG. 6 is a graph showing the relationship between the concentration of 2-methacryloyloxyethyl phosphorylcholine in the treatment solutions of example 1 and comparative example 1 and the thickness of the graft layer.

Detailed Description

Hereinafter, an embodiment of the present invention will be described in detail. In the present specification, "a to B" representing a numerical range means "a or more and B or less" unless otherwise specified.

[ 1. Method for Forming graft layer ]

In the present specification, the polymer after polymerization of the compound B is referred to as "polymer B". In the present specification, the term "graft layer" means a layer formed by graft-polymerizing the polymer B on the substrate. In other words, the graft layer is a layer containing polymer B formed on the surface of the substrate. The polymer B after graft polymerization is also referred to as "graft chain".

In the case of such a structure, a graft layer containing the polymer B can be efficiently formed on at least a part of the surface of the substrate. Specifically, the graft polymerization efficiency of the compound B is improved by the volume-excluding effect and the gel effect of the polymer C contained in the solvent D. Hereinafter, the volume exclusion effect and the gel effect will be described.

Fig. 1 is a schematic diagram illustrating the effect of the excluded volumes. The polymer C has a volume in the treatment liquid. In general, since repulsive force acts between the polymers C, the polymers C are limited in their proximity to each other. Therefore, as shown in fig. 1, the region where the compound B can be present becomes narrower in the treatment liquid 1001 to which the polymer C is added than in the treatment liquid 1000 to which the polymer C is not added. This is called the excluded volume effect. Thus, the apparent concentration of the compound B in the treatment liquid and/or the consumption rate of the compound B increases, and the graft polymerization efficiency of the compound B increases.

Fig. 2 is a schematic diagram illustrating the gel effect. As described above, since the treatment liquid contains the polymer C, the entire treatment liquid has high viscosity. Thus, since the movement of the polymer B having a growth group is restricted, as shown in FIG. 2, the termination reaction between the polymers B as a bimolecular reaction is reduced. That is, if the polymers B having a growth group react with each other, further polymerization of the terminal ends of the polymers B is terminated, but if the treatment liquid has a high viscosity, termination of the polymerization is reduced. This is called the gel effect. Thereby, the apparent consumption rate of the compound B increases.

By the above 2 elements, a graft chain having a length equivalent to the conventional one or a longer one and/or a graft layer having a thickness equivalent to the conventional one or a thicker one can be efficiently formed on the surface of the substrate containing the polymer a at a concentration lower than that of the conventional one.

< 1-1. Treatment fluid >

The treatment liquid according to one embodiment of the present invention contains a compound B, a polymer C, and a solvent D, and is a treatment liquid for forming a graft layer formed by graft polymerizing the compound B on at least a part of the surface of a substrate containing the polymer a. The treatment liquid may contain a polymer C in addition to the compound B at a stage before the graft polymerization is initiated.

By forming the graft layer using the treatment liquid of the present invention, the amount of the compound B used and the amount of waste can be reduced as compared with the prior art. That is, the productivity can be improved and the burden on the environment can be reduced. In addition, the polymerization initiator used can be reduced, the intensity of light irradiated during photoinitiated graft polymerization can be reduced, the polymerization temperature during thermally initiated graft polymerization can be reduced, and the like. Therefore, it is possible to expect reduction in substrate degradation due to light irradiation, expansion of applicable compounds, and the like.

The polymer B is formed by polymerization of the compound B. In addition, the compound B forms a graft layer by graft polymerization. The compound B may be 1 or more.

The compound B may be electrically neutral. This can reduce the interaction in or/and between the compounds B. In the present specification, "charge neutral" means a group which becomes an ion without ionization in an aqueous solution having a pH value (pH value 6 to 8) in the vicinity of neutral, or a group which becomes a cation and a group which becomes an anion, if any, and the total of charges thereof is substantially 0. The term "substantially" as used herein means that the total of charges is 0 or even if not 0, is so small that the effect of the present invention is not adversely affected.

Compound B may have a phosphorylcholine base. Thus, the graft layer can maintain high biocompatibility and/or a good lubrication state for a long period of time.

The compound B may also have a polymerization initiator group. For example, the compound B may be a polymerizable monomer having a phosphorylcholine group at one end and a polymerization initiator group capable of graft-polymerizing with a substrate at one of the other ends.

The compound B may have a polymerizable methacrylic unit as the polymerization initiator. This enables the graft layer to be easily formed.

Examples of the compound B having a phosphorylcholine group include: 2-methacryloyloxyethyl phosphorylcholine, 2-acryloyloxyethyl phosphorylcholine, 4-methacryloyloxybutyl phosphorylcholine, 6-methacryloyloxyhexyl phosphorylcholine, ω -methacryloyloxyethylene phosphorylcholine, and the like. Hereinafter, 2-methacryloyloxyethyl phosphorylcholine is also referred to as "MPC". In addition, the polymer polymerized by MPC is also called poly (MPC) or PMPC.

MPC has a chemical structure represented by the following structural formula and is a polymerizable monomer having a phosphorylcholine group and a polymerizable methacrylic acid unit.

[ chemical formula 1 ]

Since MPC is readily polymerized by radical polymerization, it is capable of forming high molecular weight homopolymers (Ishihara et al, polymer Journal 22, p355 (1990)). Therefore, when the graft layer is formed as an aggregate of polymer chains obtained by polymerizing MPC, graft bonding of the MPC polymer chains to the substrate surface can be performed under relatively mild conditions. In addition, a high density of graft chains and/or graft layers can be formed, thereby forming a large number of phosphorylcholine groups on the surface of the substrate.

The graft layer may be formed not only as a homopolymer composed of a single polymerizable monomer having a phosphorylcholine group, but also as a copolymer composed of a polymerizable monomer having a phosphorylcholine group and, for example, another vinyl compound monomer. Thus, depending on the kind of the other vinyl compound monomer used, a function such as improvement in mechanical strength can be added to the graft layer.

Further, as the compound B, polyethylene glycol dimethacrylate, a monomer having a betaine structure (methacryloxyethyl carboxybetaine, methacryloxyethyl sulfobetaine, methacryloxyethyl amidobetaine) and the like are exemplified.

The concentration of the compound B in the treatment liquid may be suitably changed depending on the type of the compound B, and may be, for example, 0.05 to 0.25mol/L, 0.10 to 0.25mol/L, or 0.10 to 0.20mol/L. If the concentration of the compound B is in the above range, the production cost and the influence on the environment can be reduced, a graft layer having a sufficient density and thickness can be formed, and the wettability and abrasion resistance of the surface of the graft layer can be improved.

The polymer C brings about the effect of removing the volume and the effect of gel as described above. The polymer C is not particularly limited as long as it is a polymer that does not interfere with the graft polymerization of the compound B. The polymer C may be an organic polymer or an inorganic polymer. From the viewpoint of solubility in the solvent D, the polymer C may be an organic polymer. The number of the polymer C may be 1 or plural.

The polymer C may be electrically neutral. The term "charge neutrality" is as described above. If the polymer C is electrically neutral, the interaction between the polymer C and the compound B or/and the polymer B can be reduced.

The weight average molecular weight of the polymer C may be 1 ten thousand or more, may be 1 ten thousand to 100 ten thousand, or may be 10 ten thousand to 100 ten thousand. With such a constitution, the effect of removing the volume of the polymer C in the treatment liquid is improved, and the graft polymerization efficiency of the compound B is improved. The weight average molecular weight can be measured, for example, by gel permeation chromatography.

The polymer C may have a phosphorylcholine group. The monomer constituting the polymer C may be the same compound as the compound B. The polymer C may be, for example, poly (2-methacryloyloxyethyl phosphorylcholine).

On the other hand, the polymer B and the polymer C may be different compounds which do not react with each other. Thus, since the compound B is used only for graft polymerization to the substrate, the graft polymerization efficiency of the compound B can be improved.

Examples of the polymer C include polyethylene glycol methacrylate, polymers having various betaine groups, starch, sucrose, and hyaluronic acid, in addition to a polymer having phosphorylcholine groups.

The concentration of the polymer C in the treatment solution may be changed as appropriate depending on the type of the polymer C, and may be, for example, 1. Mu. Mol/L or more, or may be 1 to 1000. Mu. Mol/L. If the concentration of the polymer C is within the above range, the effect of removing the volume of the polymer C in the treatment liquid can be improved, and the graft polymerization efficiency of the compound B can be improved. In addition, even when polymer B is used as polymer C, the amount of the compound B to be discarded can be reduced as compared with the case where polymer B is not used.

The concentration of dissolved oxygen in the treatment liquid before initiation of graft polymerization may be 6.0mg/L or less, or may be 0.2mg/L or less. If the dissolved oxygen concentration is within the above range, the inhibition of polymerization of the compound B by the dissolved oxygen can be reduced.

The solvent D is not particularly limited, and may be a hydrophilic solvent or a hydrophobic solvent. From the viewpoint of burden on the environment, the solvent may be a hydrophilic solvent. Examples of the hydrophilic solvent include water, saline, granulated sugar water, and a water/ethanol mixed solution. Examples of the hydrophobic solvent include alcohols, acetone, hexane, and the like. The solvent D may contain at least water.

The solvent D may be a good solvent for at least one of the polymer B and the polymer C polymerized with the compound B. The solvent D may be a good solvent for both the polymer B and the polymer C.

In the present specification, the term "good solvent" refers to a solvent having a relatively large solubility of a compound to be treated as compared with a poor solvent described below. In the above-described constitution, since a large amount of polymer B and/or polymer C can be dissolved in the solvent, the graft polymerization efficiency can be improved.

The solvent D may be a good solvent for the compound B. If the solvent D is a good solvent for the compound B, the mobility of the compound B in the solvent D is improved, and therefore the graft polymerization efficiency of the compound B can be improved.

In order to recover the polymer produced by polymerization from the solvent, a poor solvent may be used as the solvent. However, in the method for forming a graft layer of the present invention, a good solvent for polymer B can be used as described above.

The treatment liquid may further contain a soluble inorganic salt in the solvent D. This can improve the graft polymerization efficiency of the compound B.

When the solvent D is a hydrophilic solvent, a water-soluble inorganic salt may be used as the inorganic salt. Examples of the water-soluble inorganic salt include alkali metal salts and alkaline earth metal salts. Examples of the alkali metal salt include sodium salt, potassium salt, lithium salt, and cesium salt. Examples of the alkaline earth metal salt include magnesium salt, calcium salt, strontium salt, barium salt, and radium salt. In addition, when inorganic salts are classified according to the kind of counter anion, halides (for example, chloride, fluoride, bromide, iodide, etc.), phosphates, carbonates, nitrates, hydroxides, etc. are exemplified. The water-soluble inorganic salt is, for example, 1 or more selected from the group consisting of sodium chloride, potassium chloride, calcium chloride and magnesium chloride.

The concentration of the inorganic salt in the treatment liquid may be, for example, 0.01 to 5.0mol/L, 1.0 to 5.0mol/L, or 1.0 to 3.0mol/L. If the concentration is such, a graft layer having a sufficient graft density can be efficiently formed.

< 1-2. Substrate >

The substrate is the object of forming the graft layer. The substrate may contain a polymer a on at least a part of its surface. The substrate may also contain functional compounds such as antioxidants, cross-linking agents, etc., and/or reinforcing materials such as carbon fibers.

Examples of the polymer a include polyolefin and aromatic polyether ketone. The number of the polymer A may be 1 or plural. Examples of the polyolefin include polyethylene. As the polyethylene, for example, ultra-high molecular weight polyethylene (UltraHigh Molecular Weight Polyethylene, UHMWPE) is exemplified from the viewpoint of excellent mechanical properties such as abrasion resistance, impact resistance, deformation resistance, and the like. Further, as the aromatic polyether ketone, polyether ether ketone (PEEK) is exemplified from the viewpoint of excellent mechanical properties such as impact resistance and deformation resistance.

The polymer A may contain radicals. In the present specification, the term "radical" means a molecule having unpaired electrons and paramagnetic properties. The content of free radicals can be measured by electron spin resonance. The radical amount may be 1.0X10 ¹⁴ The ratio of the spin to the total spin can be 1.0X10 ¹⁴ ～1.0×10 ²⁰ The spin/g may also be 1.0X10 ¹⁵ ～1.0×10 ²⁰ spins/g。

The higher the molecular weight of the polymer constituting the base material, the higher the abrasion resistance tends to be. In the case of a polyolefin-containing substrate, the molecular weight of the polymer constituting the substrate may be 100 to 700 tens of thousands, 300 to 700 tens of thousands, and particularly 300 to 400 tens of thousands. In addition, in the case of a substrate containing aromatic polyether ketone, the molecular weight of the polymer constituting the substrate may be 5 ten thousand or more, may be 8 to 50 ten thousand, or may be 8 to 20 ten thousand. In the present specification, the molecular weight of a polymer constituting a substrate means a molecular weight determined by the following formula (1) by measuring the viscosity of a decalin (decalin) solution containing the polymer at 135 ℃.

Molecular weight=5.37×10 ⁴ X (intrinsic viscosity) ^1.49 …(1)

The density of the polymer constituting the substrate may be 0.927 to 0.944g/cm in terms of mechanical properties such as impact resistance and deformation resistance, and may be 0.927 to 0.944g/cm in the case of a polyolefin-containing substrate ³ . In addition, if the substrate contains aromatic polyether ketone, the substrate canIs 1.20-1.55 g/cm ³ 。

< 1-3. Contacting procedure >

The contacting step is a step of contacting the substrate containing the polymer a with a treatment liquid containing the compound B and the polymer C in the solvent D. In the contacting step, at least a part of the substrate may be contacted with the treatment liquid. For example, a part of the surface of the substrate in which the polymer a is present may be brought into contact with the treatment liquid, or the entire substrate may be brought into contact with the treatment liquid.

The method for bringing the substrate into contact with the treatment liquid is not particularly limited, and may be carried out by any method. From the viewpoint of efficiently forming the graft layer, the substrate may be immersed in the treatment liquid. The time for bringing the substrate into contact with the treatment liquid is not particularly limited, but may be 5 minutes or longer from the viewpoint of conducting the polymerization step described later.

< 1-4 polymerization Process >

In the step of contacting, the polymer a constituting at least a part of the surface of the substrate is graft polymerized with the compound B. The polymerization process may be performed simultaneously with the contacting process. The mode of graft polymerization is not particularly limited, and for example, photoinitiated graft polymerization may be used, or thermally initiated graft polymerization may be used.

In the case of photoinitiated graft polymerization, the polymer B polymerized from the compound B can be stably immobilized on the surface of the substrate. In addition, according to photoinitiated graft polymerization, the polymer B is formed on the surface of the substrate with a high density, whereby the density of the graft layer can be increased.

The photoinitiated graft polymerization can be initiated by visible light or ultraviolet light. When ultraviolet rays are irradiated to the surface of the substrate, the compound B in the vicinity of the surface is polymerized to produce a polymer B. The polymer B thus formed is covalently bonded to the surface of the substrate. The polymer B is grafted and combined on the surface in a high density mode to form a grafted layer which is used as a whole to cover the surface of the substrate. In this case, the substrate may be heated. By heating the substrate and the treatment liquid in contact with the substrate, photoinitiated graft polymerization can be controlled.

The surface of the substrate may contain a photopolymerization initiator. For example, a photopolymerization initiator may be applied to the surface of the substrate before the substrate is brought into contact with the treatment liquid. In this case, the radical of the photopolymerization initiator generated by irradiation with ultraviolet rays forms a polymerization initiation point on the surface of the substrate. The compound B reacts with a polymerization starting point to initiate graft polymerization to form a polymer B.

The wavelength of the irradiated ultraviolet light is, for example, 300 to 400nm. Examples of the irradiation light source for ultraviolet light include a high-pressure mercury lamp (UVL-400 HA manufactured by the company of the science of chemical engineering) and an LED (MeV 365-P601JMM manufactured by the company YEV). The irradiation time of the ultraviolet ray may be 11 to 90 minutes or 23 to 90 minutes.

The heating temperature and heating time for the thermally initiated graft polymerization are not particularly limited, but the heating temperature may be not more than the melting point of the polymer a and/or the polymer B and/or the polymer C, or not more than the boiling point of the solvent D. The heating temperature may be, for example, 25 to 150℃and the heating time may be, for example, 10 to 180 minutes.

Alternatively, the graft polymerization may be initiated by irradiation with gamma rays. The irradiation time of the gamma rays is not particularly limited, and may be, for example, 5 to 120 minutes.

After the completion of the graft polymerization, the treatment liquid may be removed by washing. Further, sterilization treatment may be performed by gamma irradiation, ethylene oxide gas, or the like.

[ 2 ] method for producing composite

The method for producing a composite according to one embodiment of the present invention is a method for producing a composite comprising a substrate and a graft layer covering at least a part of the surface of the substrate. The method for producing the composite comprises a step of forming a graft layer by grafting the polymer compound B onto at least a part of the surface of the substrate containing the polymer A by the method for forming a graft layer described above. The matters already described in [ 1 ] the method for forming the graft layer are omitted from the description below.

2-1 substrate Forming Process

In the above-mentioned production method, a commercially available product may be used as the substrate, or a substrate forming step may be included before the step of forming the graft layer. The base material can be obtained by, for example, charging a polymer a in the form of powder, granules or pellets into a mold, and then performing compression molding, extrusion molding or injection molding. The polymer a includes the UHMWPE and PEEK described above. UHMWPE and PEEK are thermoplastic resins with low flowability even above the melting temperature. Therefore, solid UHMWPE or PEEK may be put into a mold and molded under high-temperature and high-pressure conditions. Antioxidants may also be used; a cross-linking agent; the reinforcing material such as carbon fiber is put into a mold together with the polymer a.

< 2-2 Cross-linking procedure >

The method for producing a composite according to one embodiment of the present invention may include a crosslinking step of forming a crosslinked structure in the molecule of the polymer a, for example, between the step of forming the base material and the step of forming the graft layer, before the step of forming the graft layer. Thus, a substrate having further improved mechanical properties such as abrasion resistance can be obtained.

The crosslinking step may include a step of irradiating the base material with high-energy rays. This step is also called a high-energy radiation step. The radicals are generated by irradiating the substrate with high energy rays. Thus, the polymer a is bonded between the molecular chains, and a polymer a having a crosslinked structure can be obtained. When a crosslinked structure is formed between molecular chains, mechanical properties such as abrasion resistance and impact resistance are improved.

The crosslinking reaction may be carried out by adding a crosslinking agent, but there is a tendency that it is difficult to completely remove the unreacted crosslinking agent. Therefore, in consideration of the influence of the unreacted crosslinking agent on living beings, irradiation with high-energy rays may be employed to cause the crosslinking reaction.

Examples of the high-energy radiation include X-rays, gamma rays, and electron rays. The irradiation amount of the high-energy ray may be, for example, 25 to 200kGy or 50 to 150kGy. As the high-energy radiation source, for example, a radiation device using Co (cobalt) 60 as a radiation source, an accelerator for emitting an electron beam, a device for irradiating X-rays, and the like can be used as the gamma-ray source.

The crosslinking step may further include a heat treatment step after the high-energy ray irradiation step. The heat treatment step can promote intramolecular crosslinking by more efficiently consuming radicals generated by the high-energy radiation step in the crosslinking reaction. The temperature range of the heat treatment can be 110-130 ℃, and the treatment time of the heat treatment can be 2-12 hours.

[ 3 use of the Complex ]

The composite produced by the above production method can be used, for example, as a member for medical devices, a member for industrial equipment, or the like. Examples of the medical device member include an artificial joint member, an artificial blood vessel, an artificial heart, and various stents.

The artificial joint to which the artificial joint member is applied is not particularly limited, and examples thereof include artificial hip joints, artificial knee joints, artificial ankle joints, artificial shoulder joints, artificial elbow joints, artificial finger joints, and artificial intervertebral discs. For example, an artificial hip joint may be provided with a femoral head and an acetabulum. The artificial joint member according to one embodiment of the present invention can be applied to the femoral head, the acetabulum, or both. For example, when one of the femoral head and the acetabulum is used as the artificial joint member, the other may be made of a metal such as stainless steel or cobalt-chromium alloy; ceramics such as alumina and zirconia; a component containing a polymer such as UHMWPE or PEEK. In addition, for example, the femoral head and the acetabulum may be formed of different materials. For example, the femoral head may be formed of a polymeric, ceramic or metallic material, and the acetabular substrate may be formed of a polymeric material, for example.

Hereinafter, an example in which the composite body according to an embodiment of the present invention is used as an artificial joint member will be described as an acetabular cup for an artificial hip joint. Fig. 3 is a schematic view of an artificial hip joint 1 according to an embodiment of the invention. Fig. 4 is a schematic view of an acetabular cup 10 according to an embodiment of the invention. The artificial hip joint 1 is composed of an acetabular cup 10 fixed to an acetabulum 94 of a hip bone 93 and a femoral stem 20 fixed to a proximal end of a femur 91. The acetabular cup 10 has: a cup base material 12 having a generally hemispherical acetabular fixation surface 14 and a generally hemispherical concave sliding surface 16; and a graft layer 30 covering the sliding surface 16. The femoral head 22 of the femoral stem 20 is inserted into the recess 161 of the acetabular cup 10 in which the graft layer 30 is formed and slid, thereby functioning as a hip joint. The acetabular fixation surface 14 is an outer surface disposed on a side adjacent to the acetabulum 94. In addition, the sliding surface 16 is also the inner surface or contact surface that contacts the femoral head 22.

As shown in fig. 3 and 4, in the acetabular cup 10, the sliding surface 16 of the cup substrate 12 is covered by a graft layer 30. The graft layer 30 is obtained by graft-polymerizing a polymer B polymerized from a compound B onto the sliding surface 16. The graft layer 30 may be disposed only on the acetabular cup 10 or may be disposed on both the acetabular cup 10 and the femoral head 22.

The graft layer 30 has a structure similar to that of a biological film, has high affinity with the joint lubricating liquid, and can hold the lubricating liquid inside the film. In addition, the graft layer 30 has a phosphate group at a high density. Thus, the acetabular cup 10 exhibits excellent wear resistance.

Examples

Hereinafter, one embodiment of the present invention will be described in more detail based on examples and comparative examples, but the embodiment of the present invention is not limited thereto.

[ example 1 ]

As compound B, 2-Methacryloyloxyethyl Phosphorylcholine (MPC) monomer was used, as polymer C, poly MPC (PMPC) was used, and as solvent D, pure water was used. The weight average molecular weight of the polymer C is 20-100 ten thousand. PMPC, naCl, MPC was dissolved in pure water to prepare a treatment solution. The PMPC concentration in the treatment solution was set to 10. Mu. Mol/L, the NaCl concentration was set to 2.5mol/L, and the MPC concentration was set to 0.05mol/L. The polymer A has a molecular weight of 300 to 400 ten thousand and a density of 0.93g/cm ³ Square stock (section: 10 mm. Times.3 mm, length: 50 mm) of ultra-high molecular weight polyethylene was used as a base material. The prepared treatment solution was immersed in the square bar, followed by irradiation with ultraviolet rays for 90 minutes. After the completion of the ultraviolet irradiation, the square was pulled up and washed with pure water and ethanol, whereby a test piece having a PMPC graft layer formed on the surface of the substrate was obtained.

Test pieces were produced in the same manner as described above using treatment solutions in which the MPC concentration was changed to 0.08mol/L, 0.1mol/L, 0.15mol/L, 0.2mol/L, 0.25mol/L, and 0.5 mol/L.

Comparative example 1

Test pieces were produced in the same manner as in example 1, except that polymer C was not added to the treatment liquid. In comparative example 1, a test piece was also produced using a treatment liquid to which neither compound B nor polymer C was added.

[ measurement of static contact angle of Water ]

The hydrophilicity of each test piece was evaluated by measuring the contact angle (static contact angle of water) when pure water was dropped onto the surface of each test piece on which the graft layer was formed. The static contact angle of water was evaluated by the droplet method using a surface contact angle measuring device (DM 300, manufactured by the co-ordinates interface science). Specifically, according to the standard of ISO 15989, pure water in an amount of 1 μl was dropped on the surface of the test piece, and the contact angle was measured after 60 seconds.

[ measurement of the thickness of the graft layer ]

For each test piece, the test piece was embedded in epoxy resin, followed by staining with ruthenium tetrachloride. Thereafter, an ultrathin section was cut from the test piece using an ultrathin section cutter. An electron microscope image of a cut surface of the ultrathin section was obtained using a Transmission Electron Microscope (TEM) having an acceleration voltage of 100 kV. In 1 image of the obtained electron microscope image, the film thickness of the cut surface was measured at 10 points, and the average value thereof was calculated as the thickness of the graft layer.

[ evaluation results ]

Fig. 5 is a graph showing the relationship between MPC concentration and static contact angle of water in the treatment solutions of example 1 and comparative example 1. In FIG. 5, a black circle (polymer C (+)) means the result of the test piece of example 1 produced by adding polymer C, and a white circle (polymer C (-)) means the result of the test piece of comparative example 1 produced by not adding polymer C. As is clear from fig. 5, in example 1, even when the concentration of the compound B in the treatment liquid is low, a graft layer having high hydrophilicity can be formed. In particular, the contact angle of the test piece having an MPC concentration of 0.08 to 0.25mol/L in the treatment liquid shows a low value of 45 DEG or less. The contact angle of the test piece of the example in which the MPC concentration in the treatment liquid was 0.1 to 0.2mol/L showed a particularly low value.

FIG. 6 is a graph showing the relationship between the MPC concentration in the treatment liquid of example 1 and comparative example 1 and the thickness of the graft layer. The meaning of the black circles and white circles of fig. 6 is the same as fig. 5. As is clear from fig. 6, in example 1, even if MPC in the treatment liquid is at a low concentration, a graft layer having a thickness equal to or higher than that of the prior art can be formed. In particular, it was found that when the MPC concentration in the treatment liquid was 0.08 to 0.25mol/L, the thickness of the graft layer was 50 to 250nm, and the thickness of the graft layer was larger than that of the test piece of comparative example 1 to which no polymer C was added.

The present invention has been described above based on the drawings and the embodiments. However, the present invention is not limited to the above embodiments. That is, the present invention may be variously modified within the scope of the present invention, and embodiments in which technical means disclosed in the respective different embodiments are appropriately combined are also included in the technical scope of the present invention. In other words, it should be noted that various changes and modifications can be made based on the present invention easily by those skilled in the art. It is further noted that such variations or modifications are included within the scope of the present invention.

Industrial applicability

The present invention can be used as a method for forming a graft layer.

Symbol description

1 Artificial hip joint

10 acetabulum cup (component for artificial joint)

12 cup base material (base material)

30 graft layer

Claims

1. A method for forming a graft layer comprises the following steps:

a contact step of contacting a substrate containing a polymer A with a treatment liquid containing a compound B and a polymer C in a solvent D;

and a polymerization step of graft polymerizing the compound B to the polymer a constituting at least a part of the surface of the substrate in the contact step.

2. The method for forming a graft layer according to claim 1, wherein the polymer C has a weight average molecular weight of 1 ten thousand or more.

3. The method for forming a graft layer according to claim 1 or 2, wherein the solvent D is a good solvent for at least one of the polymer B and the polymer C obtained by polymerizing the compound B.

4. The method for forming a graft layer according to any one of claims 1 to 3, wherein the treatment solution further contains a soluble inorganic salt in the solvent D.

5. The method for forming a graft layer according to any one of claims 1 to 4, wherein the compound B has a phosphorylcholine group.

6. The method for forming a graft layer according to any one of claims 1 to 5, wherein the compound B has a polymerizable methacrylic acid unit.

7. The method for forming a graft layer according to any one of claims 1 to 6, wherein the polymer a is a polyolefin or an aromatic polyether ketone.

8. A method for producing a composite body comprising a substrate and a graft layer covering at least a part of the surface of the substrate, wherein the method comprises the steps of: a graft layer comprising the graft polymer compound B grafted onto at least a part of the surface of a substrate containing the polymer A by the method for forming a graft layer according to any one of claims 1 to 7.

9. The method for producing a composite body according to claim 8, wherein the composite body is a member for a medical device.

10. The method for producing a composite body according to claim 9, wherein the medical device member is an artificial joint member.

11. The treatment liquid contains a compound B and a polymer C in a solvent D, and is used for forming a graft layer formed by graft polymerizing the compound B on at least a part of the surface of a substrate containing the polymer A.

12. The treatment liquid according to claim 11, wherein the polymer C has a weight average molecular weight of 1 ten thousand or more.

13. The treatment liquid according to claim 11 or 12, wherein the solvent D is a good solvent for at least one of the polymer B and the polymer C obtained by polymerizing the compound B.

14. The treatment liquid according to any one of claims 11 to 13, wherein the solvent D further contains a soluble inorganic salt.

15. The treatment fluid according to any one of claims 11 to 14, wherein the compound B has a phosphorylcholine group.